Two types of force measuring devices are currently known. Devices of the first type comprise strain gauges affixed to elastic connecting means; by means of these gauges, the deformation of the elastic connecting means may be measured. Such measuring systems are fragile and unstable; they need to be zeroed frequently, and often have to be recalibrated. The second type of device obviates these drawbacks by making the measuring means independent of the elastic connecting means and enables up to six degrees of freedom to be measured by the relative deformation of two rigid elements. Because the elastic connecting means, in this second type of device, no longer bear the strain gauges, they may be given any shape or size; they may, in particular, be very small or very large in size.
The main disadvantage of all currently known devices of the second type is that they comprise at least as many deformation sensors as degrees of freedom to be measured, each sensor measuring only that component of force which corresponds to its axis. Furthermore, each sensor comprises several parts and has to be very carefully positioned. As soon as several degrees of freedom are to be measured, such devices comprise a large number of components, as a result of the need for a plurality of sensors, and require many mechanical means for adjusting their position.
The present invention overcomes these disadvantages at the same time as providing extremely accurate measurements.